As an in-vehicle system for automobiles, there is known an in-vehicle system which displays an operating state of a genuine in-vehicle device in a genuine in-vehicle display unit. Further, there is a case where genuine in-vehicle devices such as an in-vehicle audio device, an in-vehicle air conditioner, a genuine in-vehicle display unit and others are connected with each other through a LAN (Local Area Network) to constitute an in-vehicle LAN system. It is to be noted that the term “genuine” is used to specify a device equipped by an automobile manufacturer at the time of shipment.
Such in-vehicle LAN systems may take a configuration in which one of various kinds of genuine in-vehicle devices connected through the LAN is utilized as a main genuine in-vehicle device in order to display an operating state of itself or any other genuine in-vehicle device.
Meanwhile, in an in-vehicle system, a need in the market for replacing an existing main genuine in-vehicle device with another new non-genuine in-vehicle device is very high.
However, since a non-genuine in-vehicle device does not have a circuit configuration which can cope with a genuine in-vehicle display unit, its operating state cannot be displayed in the genuine in-vehicle display unit.
Further, in the above-described in-vehicle LAN system, when a main genuine in-vehicle device is replaced with a non-genuine in-vehicle device, operating states of all in-vehicle devices constituting the in-vehicle LAN system cannot be displayed.